This invention relates to improvements in the structure of well cars, and in particular to the braking system of those cars.
Railway well cars may be considered as upwardly opening U-shaped channels of a chosen length, simply supported on a pair of railcar trucks. Although single unit well cars are still common, there has been a trend in recent years toward articulated, multi-unit railcars which increase the number of containers per unit length of train. Further, articulated cars are cheaper to build and maintain per container slot.
Contemporary well cars may carry a number of alternative loads made up of containers in International Standards Association (ISO) sizes or domestic sizes, and of highway trailers. The ISO containers are 8xe2x80x2-0xe2x80x3 wide, 8xe2x80x2-6xe2x80x3 wide, and come in a 20xe2x80x2-0xe2x80x3 length weighing up to 52,900 lbs., or a 40xe2x80x2-0xe2x80x3 length weighing up to 67,200 lbs. Both stand-alone and articulated well cars can be all-purpose trailer on flat car (xe2x80x9cTOFCxe2x80x9d) or container on flat car (xe2x80x9cCOFCxe2x80x9d) railcars. This means that they can carry both containers and trailers or containers only. Domestic containers are 8xe2x80x2-6xe2x80x3 wide and 9xe2x80x2-6xe2x80x3 high. Their standard lengths are 45xe2x80x2, 48xe2x80x2 and 53xe2x80x2. All domestic containers have a maximum weight of 67,200 lbs. Recently 28xe2x80x2 long domestic containers have been introduced in North America. They are generally used for courier services which have lower lading densities. The 28xe2x80x2 containers have a maximum weight of 35,000 lbs.
Two common sizes of highway trailers are, first, the 28xe2x80x2 pup trailer weighing up to 40,000 lbs., and second, the 45xe2x80x2 to 53xe2x80x2 trailer weighing up to 60,000 lbs. for a two axle trailer or up to 90,000 lbs. for a three axle trailer. It is advantageous to provide well cars with TOFC and COFC hitches at both ends. This permits either a single 53xe2x80x2 three axle trailer or, or two back-to-back 28xe2x80x2 pup trailers to be loaded. The wheels of a trailer can rest in the well, with the front of the trailer overhanging decking at one end or the other of well car unit. A second trailer may rest in the well facing in the opposite direction. Altematively shipping containers, typically of 20 ft., 28 ft, or 40 ft lengths, may be placed in the well, with other shipping containers stacked on top. Further, well cars may carry mixed loads of containers and trailers.
When a long highway trailer rests in the well of one unit of a multiple unit articulated well car, the nose of the trailer is held in a king pin mount on the end structure of that same unit, and can overhang both the articulated connection and part of the end structure of the adjacent well car unit. Larger highway trailers usually imply larger loads. A deep side beam can generally carry a greater load than a shallow beam. Deep side beams generally yield a relatively deep well. A higher load capacity also tends to require the use of a larger, 38 inch wheel truck and a deeper end structure. The result is that the clearance from the top of the end structure of each well car unit to the underside of the nose of the highway trailer may be relatively small. For example, in the well car described herein, the design clearance is about 5.5 inches above the bolsters and running boards. The clearance above the shear plate is greater, approximately 13 inches plus a small amount. The versatility of a well car is improved if the well is designed to receive highway trailers of most common sizes. Similarly, the structure of the well car unit is generally designed not to foul a design envelope defined by the extent of the sizes of the overhanging noses of highway trailers whose wheels can be received in the well, whether in terms of height or width.
A standard AAR brake reservoir is a cylindrical steel tank approximately 16 inches in diameter and 34 inches long. The reservoir has an internal curved plate which divides the cylinder into two compartments. One compartment is an auxiliary compartment for containing compressed air used for service brake applications. The other compartment is an emergency compartment, also for containing compressed air, and is used in emergency brake applications when more rapid braking is required. Both the brake valve and the brake reservoir are too large to fit within the 5.5 inch height restriction of the well car described herein, beneath the nose of the overhanging trailers.
A compressed air trainline is formed when the cars of the train are coupled together. Compressed air from the locomotives is supplied through the trainline to charge the various reservoirs. The normal charge in the reservoirs is 90 p.s.i.g. When the locomotive engineer applies the brakes under normal service conditions, pressure is bled down from the train line, to 85, 80 or 75 p.s.i.g., for example. This causes the brake valve in each successive car to bleed pressure from the auxliary reservoir to the car""s brake cylinder or cylinders to match the lowered pressure in the trainline. The air bled from each auxiliary reservoir is bled to its respective brake cylinder, and causes the brakes to be applied, either gently or more firmly depending on the pressure level selected by the locomotive engineer. In normal operation it takes a significant length of time for the signal of the pressure drop in the train line to reach the last car in the train, and for the pressure to stabilize at the particular value selected by the train locomotive engineer.
The brake valve will only open the emergency reservoir when the pressure drop in the trainline is large and rapid. It is desirable that an emergency signal travel down the trainline more quickly than in normal operation. When emergency operation is selected to xe2x80x9cdumpxe2x80x9d the trainline, the brake valve not only causes both the auxiliary and emergency reservoirs to be opened to the brake cylinders, but also causes a valve to vent the trainline to ambient at that specific car, rather than having to drain all the way back to the locomotive. The rapidity of the emergency brake response is then a function of the distance between the valves that vent, or xe2x80x9cdumpxe2x80x9d, the trainline to ambient. The American Association of Railroads (AAR) standard S-401-92 requires that the length of brake pipe between any two adjacent control valves not exceed 175 feet, to give desired emergency brake performance. A more equal spacing of the brake valves leads to a more even time lapse between successive brake valve actualizations and hence a more uniform brake application from one car to the next. The term xe2x80x9cuniformxe2x80x9d means that there is less time delay in the brake application from one car to the next. This in turn results in less slack action in the train.
Traditionally, brake valves and brake reservoirs have been located on top of the end structure of the articulated well car units. The need to maintain clearance from the noses of the highway trailers, as noted above, requires a different placement. One alternative is to locate the brake valve in the space between the car units, above an articulation truck. However, the space available tends to be limited by the requirement that the cars be able to follow a 180xe2x80x2 bend radius.
In light of the foregoing, there is a need for a multiple unit articulated railcar that can satisfy the twin requirements that the brake valves and brake reservoirs not interfere with overhanging highway trailers that can fit in the very restrictive space between adjacent intermediate units and that they not be separated by more than 175 feet.
The U-shaped section of the car is generally made up of a pair of spaced apart left and right hand side beams, and structure between the side beams to hold up whatever load is placed in the well, and to carry shear between the beams under lateral loading conditions.
In earlier types of well car the side beams tended to be made in the form of a single, large beam. While simple in concept, they were often wasteful, having a large weight of material in locations where stress may have been low. It is advantageous to design a sill in the form of a hollow section, of relatively thin walls, and to provide local reinforcement where required. It is also advantageous that the hollow section be formed at the mill as a hollow tube or roll-formed section where possible, rather than welded. This often yields a saving in effort, may permit the use of a higher yield stress steal, and may also reduce the number of stress concentrations in the resulting structure. As the wall thickness decreases the prospect of buckling under buff loads increases, and measures to increase stiffness and hence to increase the buckling load would be advantageous. It would also be advantageous to provide protection for the sills to discourage damage to the sills due to clumsy loading of trailers or containers.
In the past one method of dealing with areas of higher flange stresses in the side construction stress concentration was to use a member of greater weight. As the thickness of structural members is reduced it would be advantageous to transfer loads from the railcar trucks to the bolsters, and thence to the side sills, more smoothly to discourage or reduce stress concentrations. One way to do this is to increase the depth of section at the bolster, with a consequent increase in height of the end decking.
In a first aspect of the present invention there is a main bolster for an articulation connection end of a railcar unit of an articulated railcar. The bolster is positionable to extend laterally to both sides of a central sill for mounting an articulation connector, and the bolster has a relief formed therein for accommodating a brake valve.
In an additional feature of that aspect of the invention the bolster has a distal end most distant from the center sill, and a foremost side for placement generally facing a main bolster of an adjacent railcar unit. The relief is formed in the foremost side adjacent the distal end. In a further additional feature bolster has a tapered portion is adjacent its tip.
In another aspect of the invention there is a railcar unit of an articulated railcar. The railcar unit has at least one articulation connection end. The railcar unit comprises a sill for mounting an articulated connector, and a main bolster having arms extending laterally from the sill. At least one of the arms has a relief formed therein for accommodating a brake valve.
In an additional feature of this aspect of the invention, the articulated end includes a shear plate mounted below the bolster, a lateral reinforcement mounted to the shear plate, and a pair of protruding load bearing arms extending longitudinally therefrom on either side of the sill. The relief is located outboard of one of the load bearing arms. In a further additional feature, the reinforcement is mounted above the bolster and the reinforcement has another relief corresponding to the relief of the bolster.
In a further additional feature of that aspect of the invention, the railcar unit is a well car unit. It has a well in which the wheels of a highway trailer can be placed with the nose of the highway trailer overhanging the articulation connection end in a space defined as a clearance envelope. The brake valve is mounted at least partially within the relief with all of the brake valve lying outside the envelope.
In a further additional feature of that aspect of the invention, the railcar unit further comprises a pair of longitudinal side walls. It has emergency and service reservoirs for its brakes. At least one of the service brake and emergency reservoirs is mounted to one of the side walls. In a further feature of that additional feature, the service reservoir is mounted to one of the side walls and the emergency reservoir is mounted to the other side wall.
In an alternative additional feature of that aspect of the invention, the railcar unit has a pair of end structures each for mounting to a railcar truck, and a pair of side beams extending between the end structures. Each of the beams has a top chord and a lower sill. A brake valve is mounted at least partially within the relief. Service and emergency brake reservoirs are connected to the brake valve and mounted to at least one of the beams.
In a further additional alternative feature of that aspect of the invention, each of the top chords is formed of a hollow section having an inboard portion and an outboard portion. Each beam has a web connected between the inboard portion and the lower sill. The web has an outboard face. At least one of the service and emergency reservoirs is mounted to one of the outboard faces and is at least partially overhung by the top chord.
In a further alternative additional feature of the invention the railcar unit is a well car unit having a well for receiving the wheels of a highway trailer, such that the nose of the highway trailer overhangs the articulation connection end to define a highway trailer clearance envelope. The railcar unit has a brake valve mounted to lie at least partially within the relief. All of the brake valve lies outside the envelope. The railcar unit has a service brake reservoir and an emergency brake reservoir mounted thereto outside the envelope.
In another alternative additional feature of that aspect of the invention, the railcar unit is a well car unit. It has a well for receiving the wheels of a highway trailer, such that the nose of that highway trailer overhangs said articulation connection to define a highway trailer clearance envelope. The well car unit has a pair of end structures each for mounting to a railcar truck. A pair of side beams extend between the end structures. Each of the beams has a top chord, a lower sill, and a web extending between the top chord and the lower sill. Each web has an outboard face. A brake valve is mounted to the railcar unit at least partially within the relief and completely outside the envelope. A service brake reservoir is connected to the brake valve and mounted to the outboard face of one of the webs. An emergency brake reservoir is connected to the brake valve and mounted to the outboard face of the other web. The top chord of one beam at least partially overhangs the service brake reservoir. The top chord of the other beam at least partially overhangs the emergency reservoir.
In another aspect of the invention, there is a well car unit of an articulated railcar. It comprises a pair of end structures, at least one of the end structures being an articulation connection end for connection to an articulation truck. It has a well capable of receiving the wheels of at least one size of highway trailer, the size of the noses of the sizes of highway trailer which the well is capable of receiving defining a nose overhang clearance envelope relative to said articulation connection end. The railcar includes a brake cylinder for actuating the brake of said well car unit. A brake valve is connected to control the brake cylinder and is mounted to the well car unit within half the length of the well car unit from the articulation connection end. A service brake reservoir is connected to the brake valve. An emergency brake reservoir is connected to the brake valve. The service and emergency brake reservoirs are mounted to the well car unit to lie outside the envelope.
In an additional, alternative feature of that aspect of the invention, the well car unit has a pair of side beams extending longitudinally between the end structures to define sides of the well. The service reservoir is mounted to one of the sides and the emergency reservoir is mounted to the other.
In a further alternative additional feature of that aspect of the invention, the well car unit has a pair of side beams extending longitudinally between the pair of end structures to define sides of the well. The beams have an outboard face. The service reservoir is mounted to the outboard face of one of the beams and the emergency reservoir is mounted to the outboard face of the other. In a further alternative feature of that additional feature, each of the beams has a top chord, a lower sill and a web joining the top chord and the lower sill. The top chord overhangs the one of the service and emergency reservoirs mounted to the beam.
In a further alternative additional feature of that aspect of the invention, the brake valve is mounted to one of the end structures and the reservoirs are mounted to the well car unit closer to the brake valve than to the other end structure.
In a still further aspect of the invention, there is an articulated railcar having at least two articulated railcar units sharing an articulation truck and each having an articulation connection end connected to the truck. At least one of the railcar units is a well car unit. It has a well, and a pair of end structures at opposite ends of thereof The well is capable of receiving the wheels of at least one size of highway trailer. The sizes of the noses of the sizes of highway trailer which the well is capable of receiving define a nose overhang clearance envelope relative to the articulation connection ends of the railcar units. At least one of the railcar units has a brake cylinder for operating a brake of the railcar. At least one of the railcar units has a brake valve connected to control operation of the brake cylinder. The brake cylinder valve is mounted to the one railcar unit less than half the length of that railcar unit from the articulation connection end. At least one of the railcar units has a service brake reservoir connected to the brake valve. At least one of the railcar units has an emergency brake reservoir connected to the brake valve. The brake valve, service brake reservoir and emergency brake reservoir are all mounted to the railcar in positions lying outside the envelope.
In an additional feature of that aspect of the invention, the railcar has another brake valve mounted thereto less than 175 feet from the other brake valve.
In a still further aspect of the invention, there is a railcar unit comprising a pair of ends mounted to railcar trucks, and intermediate structure connecting the. A service brake reservoir and an emergency brake reservoir are separately mounted to the railcar unit.
In an alternative, additional feature of that aspect of the invention, the intermediate structure includes a pair of side walls extending longitudinally between the ends. The service and emergency brake reservoirs are each mounted to one of the side walls. In a further, additional alternative feature, the service brake reservoir is mounted to one of the, sidewalls and the emergency brake reservoir is mounted to the other.
In yet another further aspect of the invention, there is an articulated railcar having at least two articulated railcar units. Each of the units has an articulation connection end. Each of the ends has a central sill and an articulated connector mounted therein. The railcar units share a railcar truck to which the articulated connectors are mounted. Each unit has a main bolster extending laterally of its respective central sill. At least one of the bolsters has a relief formed therein to accommodate a brake valve between the bolsters.